1. Field of Invention
The present invention relates to special-purpose boring machines and, in particular, to double-ended multiple-spindle horizontal-feed fine boring machines.
The invention may be used to the best advantage in large-scale production for fine boring and turning of precision surfaces of workpieces, e.g., of the flange, bushing, and valve fitting types.
2. Prior Art
Double-ended multiple-spindle horizontal-feed fine boring machines are widely known in the art (see, for example, the advertising publication of the EX-CELL-O company, 1974). A double-ended multiple-spindle horizontal-feed fine boring machine normally comprises a bed with outer platens and a centre platen mounted thereon for relative movement on the bearing faces of guides to effect the working feed and rapid motions, a device to receive and clamp the workpieces, mounted on the working face of the centre platen, spindle heads to hold cutting tools therein, mounted on the outer platens in such a manner that the geometrical axes of the spindle heads are parallel to the working face; the outer platens extend horizontally, and said working face of the centre platen is arranged in a horizontal plane. The term "working face" implies here and hereinafter the face of a table or a plate adapted to receive and hold various accessories and workpieces.
The main disadvantage of the above machines lies in that they are not convenient in operation, which is due to the fact that the spindle heads and the positions of the workpiece holding device are arranged horizontally in line. Thus, with more than two spindle heads, it is difficult for the operator to change the tools, set up and clamp the workpieces at the positions remote from him. This, in turn, necessitates the construction of machines with a smaller number of spindle heads, which reduces the number of workpieces which can be handled simultaneously, and consequently lowers the machine efficiency.
Another disadvantage of the prior art machines resides in an accumulation of chips and cutting fluid on the horizontally arranged working face of the centre platen, which necessitates a positive removal of chips and cutting fluid. To this effect, in the prior art machines there are provided chutes arranged at the sides of the centre platen. This, however, causes an increase of the machine width which adds to the difficulties associated with its attendance, and, along with the necessity of chip removal, brings down the machine efficiency. In addition, the difficulties in removing the cutting fluid prevent its supply at a rate required for the use of cutting tools of the most promising materials, such as cubic boron nitride, etc., which further lowers the output.
The shape of the platens and their arrangement in a horizontal plane precludes the possibility of using the prior art machines for multiple machining of workpieces without readjustment of the tools, the workpiece clamping device and the spindle drive. Readjustment of the machine for machining a workpiece, similar to the preceding one, increases the machine downtime and thus a loss in the output.
Still another disadvantage lies in that in the prior art precision multiple-spindle boring machines the guides, being arranged below the working face of the centre platen, need reliable protection and careful maintenance. This, in turn, complicates the machine design and operation and also causes downtime that reduces the output.
The principal object of the present invention is to develop a double-ended multiple-spindle horizontal-feed fine boring machine offering a higher output.
Another object of the invention is to develop a double-ended multiple-spindle horizontal-feed fine boring machine, simple in operation and attendance.
Still another object of the invention is to develop a double-ended multiple-spindle fine boring machine, wherein the shape and arrangement of the outer platens and of the centre platen ensure an easy access for the operator to the spindle heads and to the workpieces holding device.
Yet another object of the invention is to develop a double-ended multiple-spindle fine boring machine, wherein the descent of chips and cutting fluid from the working face of the centre platen by gravity would be ensured.
A further object of the invention is to develop a double-ended multiple-spindle fine boring machine suitable for machining the workpieces of the same type without resetting the tools and the device for setting up and clamping the blanks.
Still further object of the invention is to develop a double-ended multiple-spindle fine boring machine enabling a scratch-free withdrawal of the tools from the surface of machined workpieces.